Single tubing stethoscope



Feb. 3, 1970' E. s.- M'EN-D'ELSON ET Al,"

SINGLE TUBING STETHOSCOPE I Filed Dec.. 26, 1967 INVENTORS EMANUEL S. MENDELSON RAYMOND WILSON ATTORNEY United States Patent 3,493,075 SINGLE TUBING STETHOSCOPE Emanuel S. Mendelson, Harleysville, Pa., and Raymond Wilson, Westville, N.J., assignors to the United States of America as represented by the Secretary of the Navy Filed Dec. 26, 1967, Ser. No. 693,393 Int. Cl. A61b 7/02 US. Cl. 181-24 1 Claim ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates particularly to single tube, single stem binaural stethoscopes of precisely determined geometrical size and shape for use in auscultatory medical diagnosis.

Conventional stethoscopes comprise two broad classes. In one class, a single tube conducts sound from the examiners chestpiece to a Y-tube bifurcation and binaural section, from which two sound conducting tubes lead to the examiners ears. In the other class, the chestpiece has a double stem which connects with two sound conducting tubes, one going to each ear of the examiner directly through the binaural section. Presently, standard stethoscope design requires sound conducting tubing having the same internal diameter or bore throughout the entire body of the stethoscope, regardless of class or type used. As a result, even though the twotube, double-stem class is more inconvenient to carry and manipulate, it is considered by many to be more effective acoustically. The reason for the poorer acoustic performance of the single-tube stethoscope when compared to a stethoscope of the two-tube class can be attributed to the sudden doubling of cross-sectional sound conducting area as the transmitted sounds traverse the bifurcation toward the ears of an examiner.

In addition, all present binaural stethoscopes in use are formed as assemblages of separate parts comprising metal, rubber and plastic components. To function most elfectively, there should be no leakage of air, and hence of sound, through any of the components or their connec tions with each other. Nor should there be any surface irregularities, ringed grooves or sharp edges present in the internal sound conducting channels of the instrument. The aforementioned defects cause turbulent flow, acoustic reflections and power losses during the transmission of signals, thereby distorting and debasing these signals prior to reception by the examiner.

It is therefore a principal object of the present invention to provide a novel and improved binaural stethoscope of the single tube, single stern class having increased acoustic performance so that the stethoscope is not inferior to one of the double tube, double stem class.

It is a further object of the present invention to provide a novel and improved single tube, binaural stethoscope which is relatively simple in construction and yet highly agcurate and reliable in use. 7

It is another object of the present invention to provide a novel and improved single tube, binaural stethoscope having a continuous monolithic body which reduces distortion in the transmitted acoustic signal.

3,493,075 Patented Feb. 3, 1970 "ice Other objects and many of the attendant advantages of this invention Will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIGURE 1 of the drawing is a view of a binaural stethoscope showing, partially in section, one embodiment of the present invention;

FIGURE 2 of the drawing is a view of a binaural stethoscope showing, in section, another embodiment of the present invention; and

FIGURES 3 and 4 of the drawing are modifications of FIGURE 2.

Referring now to the details of the drawing, wherein like reference numerals apply to like parts throughout, and more particularly to FIG. 1, it will be seen that there is shown there a binaural stethoscope which includes a sound detecting means 10 and a single sound conducting stem 11 whose one end is connected thereto. The other end of the stem 11 is connected to a single tube or sound conducting channel 12 to which there is also connected a Y-connecter or bifurcation 13 which separates the transmitted sound for binaural presentation to the ears of an examiner. Also connected to the bifurcation 13 are two sound conducting channels 14 which form the binaural section of the stethoscope and which carry earpieces 15 at their free ends adapted to be inserted into the ears of the examiner.

It will thus be understood from the structure described i that sound will be transmitted from the sound detecting means 10 through the channel 12, the bifurcation 13 and the channels 14 to the respective earpieces 15. As previously disclosed, the sudden doubling of the cross-sectional sound conducting area as the transmitted sounds traverse the bifurcation toward the ears of an examiner is the cause of comparatively poor acoustic performance. Therefore, the improvement contemplated by the embodiment shown in FIG. 1 is to establish equal cross-sectional sound conducting areas both above and below the division point of the bifurcation. The stem 11, the single sound conducting channel 12 and the vertical section of the bifurcation 13 all have the same internal diameter. This dimension is selected to be substantially 1.414 times larger than the internal diameter of each diagonal outlet section of the bifurcation 13 and the binaural conducting channels 14. Thus, the combined cross-sectional area of the sound conducting channels 14 is substantially equal to the cross-sectional area of the single sound conducting channel 12 which results in an acoustically symmetrical stethoscope thereby improving performance by eliminating the aforementioned doubling of cross-sectional area.

Referring nOW to FIG. 2 of the drawing, another embodiment of the invention is shown to provide increased acoustic performance. The internal dimensions of the sound conducting channels and operation of FIG. 2 is substantially the same as that described hereinabove except that instead of an assemblage of separate parts, the complete body of the stethoscope comprises one continuous and bifurcated tube or sound conducting channel made of a flexible rubber or plastic material or the like. For example, by using standard dip-mold processes, the monolithic body may be formed from natural or synthetic latex rubber or silicone. The integral body comprises a single sound conducting channel 12 which divides into two sound conducting channels 14 at the bifurcation 13. The sound conducting channels 14 terminate in integral eartips 15 which fit into the ears of an examiner, or a separate conventional eartip may be added as shown in FIG. 1 to insure that no sound leakage results at reception.

The sound conducting channel 12 terminates in a chestpiece opening 16 to which a real or nominal diaphragm may be integrally formed or attached as shown in FIGS.

3 and 4,- to which-reference is now made. FIG. 3 shows an open bell type chestpiece 17 which is integrally and continuously formed across the chestpiece opening 16. The stethoscope shown in FIG. 4 has a plastic diaphragm 17a or the like which is attached to the chestpiece opening 16 by any conventional mechanical means 18. The selection of the type of chestpiece to be employed is dependent on the source and frequency of the sound to be received by the examiner, and in no way limits the application of the stethoscope as described.

The internal dimensions of the sound conducting channels of FIG. 2 are the same as those in FIG. 1, that is, the diameter of the sound conducting channel 12 is 1.414

times larger than the diameter of the channels 14, thereby resulting in an equal cross-sectional sound conducting area both above and below the bifurcation 13. FIGS. 3 and 4 modify the single unit body of FIG. 2 by changing the internal dimensions and shape of the conducting channels. FIG. 3 shows a binaural stethoscope of the monolithic unit'design having equal conducting channel diameters throughout. FIG. 4 shows a monolithic stethoscope having a continuously expanding sound conducting cross-sectional area. That is, the diameter and therefore the combined cross-sectional area of the conducting channels alongside the entire length of the stethoscope is gradually increased from the chestpiece opening 16 to the eartips 15. It is preferred that the cross-sectional area at the division point of the bifurcation be equal to the maximum cross-sectional area of the sound conducting chanel 12 and to the combined minimum cross-sectional area of the two sound conducting channels 14 so that there is a smooth transition of the acoustic signals into binaural presentation. The use of a continuously expanding cross-sectional area will distribute the signal resonance along the entire conduction channel length with increased stethoscope signal-to-noise ratio, thereby further improving the acoustic performance.

What is claimed is:

1. In a single tube, single stem binaural stethoscope, the improvement wherein:

I (a) the complete body of the stethoscope between the chestpiece opening and the openings in the eartips comprises a single, continuous, monolithic unit having sound conducting channels with continuously expanding cross-sectional areas, said cross-sectional areas increasing from the chestpiece opening out to the division point of the bifurcation for the single sound conducting channel and from the division point out to the eartip openings respectively for each of the remaining pair of sound conducting channels;

(b) and wherein the diameter of the single sound conducting channel at the division point of the bifurcation is substantially 1.414 times larger than the diameter of each of the remaining pair of sound conducting channels at the division point.

References Cited UNITED STATES PATENTS 8,591 12/1851 Marsh 181-24 350,393 10/ 1886 Radzinsky 181-24 2,363,686 11/1944 Olson 181-24 3,169,600 2/ 1965 Thomas 181-24 FOREIGN PATENTS 580,594 7/1933 Germany. 255,086 3/ 1963 Australia.

STEPHEN J. TOMSKY, Primary Examiner 

